The present invention relates to high tenacity monofilaments suitable for a variety of applications including use as reinforcement in rubber products. More particularly, the invention relates to monofilaments with high tenacity and an oblong cross-section and a rubberized fabric containing such monofilaments.
Nylon or polyester multifilament yarns are typically used in ropes, cables, braided structures, and industrial fabrics and for reinforcement of tires, belts, hoses and other mechanical rubber products. For use as rubber reinforcement, cords are produced from the multifilament yarns which are comprised of an appropriate number of singles yarns plied together to produce total deniers ranging from about 1500 to about 6000 or more. In such cords, the yarns and the cord itself is twisted and has a generally round shape in cross-section.
While it is otherwise advantageous to produce multifilament cords higher in denier to increase strength, the resulting thick, generally round cross-section cords have several disadvantages. Bending moment increases exponentially with the thickness and, consequently, there is difficulty in fabricating and manipulating articles reinforced with such cords. Due to the thickness, tires incorporating such cords require more rubber than is otherwise needed which increases the cost and results in heat build-up in the tire in use. In non-rubber applications, products containing multifilament yarns of all deniers are subject to damage by abrasion.
High tenacity monofilaments are known as an alternative to multifilament yarns. The use of monofilaments in tires is disclosed in U.S. Pat. Nos. 4,009,551 and 4,056,652 and in Product Licensing Index, April 1972. Co-pending application Ser. No. 106,661 discloses a radial tire containing monofilaments. However, known high tenacity monofilaments have not provided sufficient improvement over multifilament yarns to be employed widely. Other known uses of monofilaments include tennis racket strings as disclosed in U.S. Pat. No. 4,055,941 containing from two to four monofilaments and as fishing line as disclosed in co-pending application Ser. No. 106,653.